Active sensing can be used to determine three dimensional models. Active sensing systems include, for example, time-of-flight systems and structured light systems. In order to extract a three dimensional (3D) model of an object, multiple active sensing devices may be used. Some embodiments of a depth sensing system (also referred to as depth cameras) use an infra-red (IR) transmitter to project an invisible IR structured light pattern into the environment and onto an object. The IR radiation reflected from the object is detected by an IR sensor or camera of the depth sensing system. Objects within the environment cause distortions in the structured light pattern as seen by the camera, which is off-axis compared to the light source and these distortions can be used to resolve depth information about the scene.
A depth sensing system having a single camera has a limited field of view and provides depth information from a single viewpoint so that an object which is close to the depth camera may occlude a large portion of the environment. One solution which extends the area of the environment which can be mapped is to use more than one IR depth camera. This provides views of the scene from different perspectives and enables a 360 degree model of an object to be formed. However, in certain configurations the multiple devices used in active sensing may interfere with one another. In addition, where the structured light patterns overlap, the accuracy of each IR depth camera is degraded.
Accordingly, it would be advantageous to have depth sensing systems that overcome these issues. The embodiments described below are not limited to implementations which solve any or all of the disadvantages of known IR depth camera systems.